Remove get_poloidal_comm from MPI Topology
Remove get_poloidal_comm from MPI Topology

Seems to serve no purpose and isn't used anywhere

feltor-dev/feltor,mwiesenberger/feltor,feltor-dev/feltor,feltor-dev/feltor,mwiesenberger/feltor,mwiesenberger/feltor,mwiesenberger/feltor,feltor-dev/feltor